Method for preparation of metallic and ceramic foam products and products made

Abstract

The present invention relates to the fabrication of low cost, in situ, porous metallic, ceramic and cermet foam structures having improved mechanical properties such as energy absorption and specific stiffness. Methods of fabricating the structures from compositions including ceramic and / or metallic powders are provided. The flowable compositions also include an immiscible phase that results in pores within the final structure. Furthermore, the structures may be shaped to have external porosity, such as with mesh-like structures.

Description

FIELD OF THE INVENTIONThe present invention relates to the fabrication of low cost, in situ, metallic foam components having oriented microstructures and improved mechanical properties such as energy absorption and specific stiffness. The present invention also relates to the fabrication of low cost, in situ, ceramic and, cermet foam components with improved mechanical properties.BACKGROUND OF INVENTIONCellular materials have been available for decades, but new opportunities for cellular materials are emerging. Novel manufacturing approaches have beneficially affected performance and cost. Additionally, higher levels of basic understanding about mechanical, thermal and acoustic properties have been developed. These provide an integrated pathway between manufacturing and design.Cellular materials have high stiffness and yield strength at low density relative to other competing materials and systems. That is, the cellular materials may be laminated between opposed sheets of another ma...

AI Technical Summary

Benefits of technology

The present invention overcomes the problems encountered with conventional methods and compositions by providing efficient, cost-effective processes for preparing complex metallic, ceramic and cermet foam components with optimized dynamic mechanical properties. More specifically, the invention provides methods and compositions for metallic, ceramic and cermet foam components. In particular, the present invention relates to the freeform fabrication of metallic, ceramic, and cermet foams to form parts having complex geometries and that demonstrate superior mechanical properties and energy absorbing capacity.

Further, the present invention provides cost-effective methods of producing ultra-lightweight structures directly from CAD designs and offers the ability to manufacture complicated shape prototypes with minimal post-processing steps. In addition, the present invention provides methods and compositions for forming foam structures that have both open and closed cell porosity. The porous nature of the structures enhances their energy absorbing and blast amelioration capability and other mechanical properties such as compressive strength.

Accordingly, an object of the present invention is to fabricate metallic, ceramic, and cermet foam components with optimized mechanical properties in an efficient, cost-effective manner.

Problems solved by technology

Novel manufacturing approaches have beneficially affected performance and cost.

It is very difficult to control pore size or orientation using these known techniques.

Again, this process has little control of the pore size or orientation.

Furthermore, this method can be cost-prohibitive if used to create geometrically complex parts due to the molds required.

However, this process, referred to as the GASAR process, involves the use of molten metals and the injection of gases, and is therefore, technically complex and expensive.

Furthermore, the GASAR process allows the use of only one pore or cell orientation in a component and the shapes of the components are generally limited to plates, rods, and tubes.

Methods of making ceramic foams and cermet foams, which contain both metallic and ceramic materials, encounter similar difficulties.

Such methods are extremely complex and do not produce products with predictable quality or predictable porosity.

Further, prior cermet foams utilize a foaming agent, and thus both the shape and the amount of porosity can not be controlled.

As a result, it is difficult to make foams that have consistent mechanical properties.

Additionally, the manufacture of complex shaped foams using those methods is not feasible.

While others have developed processes for the fabrication of metallic foam structures with oriented porosity, none of those processes are capable of creating a combination of open and closed cell porosity, nor are they capable of creating components directly from CAD designs.

Additionally, control of pore size and pore orientation is difficult.

Moreover, conventional processes do not provide for the fabrication of integral structures with a metallic foam skin in a cost-effective manner.

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